1. Field of the Invention:
This invention relates to an engine mounting for motor vehicles, the engine mounting comprising an elastic rubber bearing having a first member adapted to be secured to the vehicle chassis and a second member adapted to be connected to the vehicle engine. The first and second members can be connected to one another by means of at least one elastomer spring and a hydraulic damping apparatus. The hydraulic damping apparatus can have two chambers located adjacent one another and filled with damping fluid, and the two chambers can be connected to one another by means of a damping passage.
2. Background Information:
Known engine mountings, such as the one disclosed in Federal Republic of Germany Patent No. 30 24 090, which corresponds to U.S. Pat. No. 4,378,936, include elastic rubber bearings in which the fastening parts are connected to one another by means of an elastomer spring, and in which there is also disposed some sort of hydraulic damping apparatus. The elastomer spring basically consists of an outer, one-piece or multi-piece shear or thrust spring and an inner, ring-shaped rubber spring, which inner spring is essentially supported between a main body portion of the damping apparatus and one of the fastening parts. As a result of this configuration, the inner, ring-shaped rubber spring can absorb only a small proportion of the bearing load, whereby an effective damping of low frequency, high amplitude vibrations is achieved, while avoiding the damping of high frequency, low amplitude vibrations.
A bearing such as this can be viewed as having essentially three shear directions: a first, vertical or z direction in which the load of the engine is supported; a second, longitudinal or y direction in which the lateral load from cornering is supported; and a third, transverse or x direction perpendicular to both the z and y directions. As such, a disadvantage of such a bearing is that there is essentially no damping in the soft shear, or x direction, so that on account of the soft, low spring constants of the elastomer spring, large undamped movements between the fastening parts are possible. It is these large undamped movements which can result in a build up or amplification of resonance between the two bodies connected by the bearing.